Circumzenithal Arc Over Saint-Hubert, Quebec

October 12, 2014

Epod (2)

: Manon Boily
Summary Authors: Manon Boily; Jim Foster

Shown above is a striking circumzenithal arc (CZA) as seen from Saint-Hubert, Quebec, Canada. I went outside to put my wet clothes on the washing line when I saw this colorful arc high in the sky as the Sun was approaching the horizon. Note that the red side of the arc is closest to the Sun. CZAs are the brightest of all the ice crystal halos and arcs. They look almost as if they've been painted in the sky. In order to see this arc, sunlight must enter the upper basal faces of similarly aligned, hexagonal (plate-shaped) ice crystals in cirrus clouds and then exit through one of the crystals' side faces. Photo taken at 5:30 p.m.
Photo details: Camera Model: Canon EOS 450D; Lens: EF-S18-55mm f/3.5-5.6; Focal Length: 18mm; Aperture: f/3.5; Exposure Time: 0.0006 s (1/1600); ISO equiv: 100; Software: Adobe Photoshop Elements 11.0 Windows.